Doctors should assess their dementia patients for road readiness, a new study suggests, as older drivers with dementia are more likely to be in a car accident.
Researchers, led by Dr. Mark Rapoport of Sunnybrook Health Sciences Centre, found that dementia patients who were taking antipsychotic or antidepressant drugs were 50 per cent more likely to be in a collision.
In some provinces, such as Ontario where the study was conducted, doctors are required to report patients they feel are unfit to continue driving to the Ministry of Transportation.
The findings show that many patients with dementia stay on the roads, the researchers said.
"The problem is that we found at least 2,500 patients on the road who had car crashes on these medications," Rapoport, a psychiatrist at Sunnybrook and a professor of psychiatry at the University of Toronto, told CTV.ca. "So even though there is that duty to report, it's not happening. And these are only the patients who have been diagnosed by their physician."
Researchers from Sunnybrook, the University of Toronto and the Institute of Clinical Evaluative Sciences (ICES) used data from the Ontario Ministries of Health and Transportation to complete the study. The findings are reported in a letter to the editor in the October issue of the Journal of the American Geriatrics Society.
Patients with dementia experience two types of symptoms: cognitive symptoms, which include memory loss and getting lost, and behavioural difficulties, which include depression, psychosis, aggression, agitation and sleep disturbances.
At least half of those with dementia will experience behavioural problems, Rapoport said.
For their study, the researchers set out to determine if there is a link between taking medications for those behavioural symptoms and motor vehicle accidents.
They analyzed data from nearly 8,700 Ontario drivers who had been diagnosed with dementia by their doctors.
The drivers were aged 65 and older, lived in their own homes, had a valid driver's licence and had been in a car accident at age 67 or older during the eight-year study period.
They found that one in five dementia patients had an active driver's licence. Of those patients:
- One in four had been in at least one car accident.
- One in three who had been in an accident had been prescribed a medication to treat behavioural problems.
The study cannot answer the question of whether the drugs or the symptoms led to the increased accident risk, Rapoport said.
However, the researchers found that people on antidepressants had an 82 per cent increased risk of getting into an accident, while those on sleeping pills, which are known to put drivers at risk, had only a 12 per cent increase in risk.
The researchers also know from previous studies that people with behavioural difficulties are more at risk of getting into a car accident.
"So we suspect that it's not the pharmacology, it's not the drug itself. It's actually what's driving the prescription," Rapoport said. "So a depression would be worse than a slightly anxious person and even worse than depression is someone who is hallucinating or delusional with their dementia, in which case we had an almost three-and-a-half fold increase in risk."
Rapoport and his colleagues recommend that doctors and family members advise dementia patients to stop driving, particularly if they exhibit behavioural symptoms.
"The bottom line," Rapoport said, "is when someone has dementia and a behavioural disturbance or is taking a drug for a behavioural disturbance, it's time to really give up the keys."
